The present invention relates to a method of an apparatus for regenerating charged adsorbents, particularly activated coal charged with gaseous pollutants such as sulfur dioxide.
There have been already proposed various methods and arrangements for desorbing charged adsorbents. So, for instance, it has been proposed to regenerate or desorb charged active coal by contacting the same with a finely pulverized heat carrier which is at a temperature exceeding 500.degree. C. In this proposed arrangement, the active coal to be regenerated is introduced into a desorbing vessel from an intermediate or an accumulating container, and the desorption gas which is liberated from the adsorbent during the thermal treatment thereof is withdrawn from the desorbing vessel and subsequently subjected to a further treatment.
This proposed method is used, and the arrangement performing such method is employed, for instance, in connection with de-sulfurizing flue gases, particularly those generated during the operation of a boiler installation of an electric generating plant. In this application, the flue gases are conducted through a body or heap of particulate or granular activated coal or activated coke. During the passage of the flue gases through such a body, sulfur dioxide as well as the present sulfur trioxide and other pollutants or impurities are adsorptionally attached to the activated coal or activated coke particles or granules and thus removed from the flue gases.
As already mentioned above, the regeneration of the charged adsorbent, such as the particulate or granular activated coal or activated coke can be achieved in a thermal manner, for instance, by contacting the charged adsorbent with a particulate heat carrier, and finely granulated or finely particulate sand can be used as the heat carrier. Experience with this method and with the operation of the apparatus employing this method has shown, however, that the desorption gas leaving the body of the adsorbent contains, in addition to water vapor, carbon dioxide and sulfur dioxide, also sulfur trioxide and dust. The two last-mentioned components of the desorption gas issuing from the body of the adsorbent render further treatment of the desorption gases difficult if not impossible.